Delta OHM HD32.3, Руководство по эксплуатации

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HD32.3
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V1.4
From PMV comes a second index called PPD (Predicted Percentage of Dissatisfied) which calcu-
lates in percentage the “dissatisfied” beings in relation with precise microclimatic conditions.
ISO 7730 regulation suggests the PMV use in presence of the following environments with vari-
ables variations that influence the thermal balance:
•
Energetic waste = 1 ÷ 4 met
•
Thermal impedance by clothing = 0 ÷ 2 clo
•
Wet bulb temperature = 10 ÷ 30°C
•
Medium radiant temperature = 10 ÷ 40°C
•
Air speed = 0 ÷ 1 m/sec
• Vapour pressure = 0 ÷ 2,7 kpa
So, PMV is an index suitable to the evaluation of working environments with moderate microcli-
mate such as houses, schools, offices, laboratories, hospitals, etc.; it’s useful in detecting limited
degrees of thermal discomfort in the people in this environment.
ISO7730 regulation suggests PPM values b 0,5 and - 0,5 for the thermal comfort state and
to these values correspond a percentage of dissatisfied about the thermal conditions (PPD) less than
10% (see the following table).
Table 1: thermal environment evaluation scale
PMV PPD % THERMAL ENVIRONMENT EVALUATION
+3 100 Hot
+2 75,7 Warm
+1 26,4 A little bit warm
+0,85 20 Acceptable thermal environment
-0,5 < PMV < +0,5 < 10 Thermal well-being
-0,85 20 Acceptable thermal environment
-1 26,8 Cool
-2 76,4 Cold
-3 100 Very Cold
For the calculation of PMV and PPD indexes, it’s necessary to know:
•
The working charge (energetic waste);
•
The thermal impedance of clothing.
The working charge can be calculated using the following measurement units:
kcal/h (1 kcal/h = 1.163 Watt): with this unit is expressed the medium power per hour supplied
during the working activity;
MET (1 MET = 58.15 Watt/m
2
): with this unit is expressed the total power per hour supplied by a
being during the working activity divided for the body surface of the being.
Thermal impedance of the clothing is measured in CLO;
1 CLO = thermal gradient of 0.18 °C on a 1 m
2
area crossed by 1 kcal/h thermal flow
The following tables can help to establish the thermal impedance values of the clothing and the
working rate (metabolism).